What is a primary purpose of indexes in relational databases?

What is a primary purpose of indexes in relational databases?

• A. Find Data faster
• B. Increase storage without performance impact
• C. Decrease query performance
• D. Are deprecated in modern DBs

Answer: (A)

Indexes in relational databases help the system locate rows quickly without scanning the entire table. They do this by maintaining a separate data structure that maps index column values to the locations of the corresponding rows, enabling the query planner to jump straight to the matches. This makes lookups on indexed columns much faster, especially for WHERE predicates, joins, and sorting. There are tradeoffs: indexes consume extra storage and require maintenance on write operations, so they may not improve performance for every query, particularly on low-selectivity columns. The other options aren’t accurate because indexes add storage and upkeep rather than being storage-free, they don’t inherently slow down queries, and they are still widely supported in modern databases.

Indexes in relational databases help the system locate rows quickly without scanning the entire table. They do this by maintaining a separate data structure that maps index column values to the locations of the corresponding rows, enabling the query planner to jump straight to the matches. This makes lookups on indexed columns much faster, especially for WHERE predicates, joins, and sorting. There are tradeoffs: indexes consume extra storage and require maintenance on write operations, so they may not improve performance for every query, particularly on low-selectivity columns. The other options aren’t accurate because indexes add storage and upkeep rather than being storage-free, they don’t inherently slow down queries, and they are still widely supported in modern databases.